SEBASTIAN MIHAI, DENISA DUMITRESCU, MADALINA ANA RADUCANU, IULIANA STOICESCU, VICTORIA BADEA PHYTOCHEMICAL PROFILE AND TOTAL ANTIOXIDANT CAPACITY OF SEMPERVIVUM RUTHENICUM KOCH HYDROETHANOLIC EXTRACT The scope of this work is a phytochemical analysis and antioxidant activity assay of a Sempervivum ruthenicum Koch hydroethanolic extract. The hydroethanolic extract was prepared from the dried leaves of the plant by maceration in a water and methanol mixture (50:50 v/v). The total phenolic content of the extract was calculated to be 3.0501±0.0272 mg/mL and the total flavonoid content was determined in a concentration of 3.113±0.0394 mg/mL. The HPLC-DAD analysis revealed phenolic acids and flavonoids, which were quantified. The most prevalent phenolic acids in the extracts were gallic and ellagic acids, with concentrations of 1.2443±0.0475 mg/mL, respectively 0.6339±0.0026 mg/mL. The heteroside astragalin was present in high concentration of 1.1934±0.0754 mg/mL. The DPPH free radical scavenging assay revealed the EC50 value of the extract to be 2.5788±0.003 mg/mL. These results suggest a good scavenging ability of the extract, which is due to the abundance of polyphenolic compounds. The antioxidant activity of the extract demonstrates a high scavenging ability at low doses. Sempervivum ruthenicum Koch shows a promising phytochemical profile that suggests it’s use in pathological conditions that involve high oxidative stress.